An affordable upper assembly without cutting corners. This means using a nitrided steel gas block from an American Manufacturer as opposed to aluminum, quality American Made handguards, and using a quality NBS M16 profile Black Nitride BCG paired with a 416R Stainless Steel Midlength barrel chambered in 5.56 with a 1:7 twist rate.This also means taking the time to ensure that the upper will function reliably. We use Permatex 242 on key components while using mil-spec AEROSHELL 33MS Anti-Seize grease on the properly torqued barrel nut and muzzle device.Bottom line is this: you hear all the time about guys buying a budget upper and it not lasting or having to send it back because of some hardware defect or other issue caused by a careless assembly process. That is why we use brand name components, assemble each unit to the highest standard of quality, and why we don't sell our uppers without pairing it with a BCG. We want your upper to function flawlessly out of the box. In fact, we guarantee it will.Lifetime WarrantyGuaranteed Sub-MOA performance with match grade ammo and proper shooting techniqueUpper ReceiverNBS Slick Side Billet Upper- 6061 Aluminum- Pairs beautifully with any mil-spec lower- M4 FeedrampsBarrel16" 5.56 NATO 1:7 Twist Mid-Length 416R Stainless- Guaranteed to hold a 1.000" MOA at 100 yards with appropriate ammo and shooting techniques.Bolt Carrier GroupNBS Black Nitride M16 Bolt Carrier Group .223/5.56- 9310 MPI Tested Bolt- Case Hardened 8620 Carrier- 4130 Gas Key- Grade 8 Hardware With Proper Staking- Gas Key Sealed With Permatex No.3- 8740 Hard Chrome Firing PinCharging HandleMil-specGas SystemMid-Length- APOC Armory Nitrided Steel Gas Block- Stainless Steel Mid-Length Gas TubeHandguardNBS M-LOK Free Float Handguard- American Made- 6061 Aluminum- Style may vary by batchMuzzle DeviceMil-Spec A2 Birdcage w/ Jet Black Nitride FinishHandguard style may vary by batch